Many current XAO systems (for example the Gemini Planet Imager[1]} and SPHERE[2]}) see their overall performance limited by temporal effects, termed bandwidth error. While faster computers and deformable mirrors, as well as increasingly efficient readout
detector technology can shorten an AO system's lag time, often the system lag is dominated
by how long a wavefront sensor needs to expose to get a high signal-to-noise
wavefront measurement. Predictive control can mitigate the bandwidth error without reducing the wavefront sensor exposure time, by
predicting the wavefront of the system one step into the future. While some
atmospheric turbulence will always be stochastic, the bulk motion is accurately represented[3]} by the simple Frozen Flow Hypothesis[4]}, wherein we imagine
static phase screens translating across the telescope pupil at the velocity of their associated wind layers. It is therefore reasonable to conclude that previous measurements of the wavefront contain information that can be used to predict the future shape of the wavefront.
